Accelerated corrosion tests including the neutral salt spray test ISO 9227 or cyclic corrosion tests (ISO 20340-Annex A or NACE SP0108) are conducted to assess the performance of marine paints. Several studies sponsored by the French Navy have been conducted during the last 5 years aiming to develop more reliable testing conditions. The unreliability of the neutral salt spray test to mimic field exposures was demonstrated, implying that this test should not be used for prediction. On the contrary, a satisfying correlation to atmospheric field exposure on a ship in service was observed using a 6 months cyclic test from the automotive industry (e.g. Volvo STD23-0014) with a deviation inferior to 25% and an acceleration factor of 4. In view of optimizing testing conditions, a large project name Corrosion Control of Navy Ship was initiated in 2013. One task aimed at shortening the test duration by increasing the acceleration factor of the test without losing correlation to field. Thus, a design of experiment was used to study key parameters such as NaCl concentration, the mode of application and frequency and the temperature. Ten different marine paint systems used for shipbuilding were selected. The results indicated an enhancement of the aggressiveness of the test when doubling the salt concentration from 1 to 2wt%, increasing the number of salt spray per week (from 2 to 3) and the temperature from 35 to 45°C while keeping a rather satisfying correlation to field exposure.
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